OK, so my Dad has a short tail 331 Industrial HEMI, I believe with standard car heads. He bought the motor with the cylinders bored .040 over, new pistons/rings, etc. It, apparently, has developed some cylinder wall damage recently. How much further can he go? Can it be sleaved in order to retain the current piton/ring combo? Before it was installed, he had the block and crank checked out / balanced and assembled with mostly new parts. After assembly, the engine ran for months in the car before the car was driving. He put it on the road and racked up 300+ miles. All seemed fine. One morning he was backing it out of the garage and it kept stalling when he put in gear. He put it back, and took the daily to work. After taking everything back apart, they found a couple of wrist pins in the oil pan, as well as a cap from a silicone tube. He brought the engine into a reputable engine builder who has diagnosed the cylinder wall damage. I don't yet know the extent of the damage, and would assume its only the 1 cylinder affected.
I've heard of guys boring them .125 over and using 354 pistons, but I'd want to sonic check it first if it were mine. If only one hole has problems, I'd sleeve it.
How far you can go will depend on a sonic check. +.060 is pretty standard. With a good sonic check you can go to as much as .125" over and drop 354 pistons in there, but that's generally the VERY max and certainly shortens the life of the block as well as any number of things. If you can get away with sleeving the one hole (about $100 or so, depending on your machine shop) then you could take it back to the original number, re-ring, and not have to buy a whole new set of pistons and you wouldn't even need a sonic check because you know you're already good at that number. I wouldn't go over any more than you have to unless you really need the cubes for some reason.
Keep in mind... they only make certain standard ring sizes, so if you end up over-boring again and getting new pistons, you want to do something that's already available so you don't have to have custom rings AND custom pistons.
One more thing, make no assumptions! Make SURE it's only one cylinder and that you don't have metal from whatever destruction was caused in the engine. Two wrist pins would imply more than ONE cylinder, so that just sounds weird.
Time for TOTAL disassembly. Start from the beginning, check everything twice, mag everything remotely close to the two cylinders. Wrist pins do not just fall into the pan, it had to have made some horrific noise when things went wrong. Silicon tube cap? God only knows what kind of mess you will turn up with that as a headliner...did I say check everything twice? If you find that silicone shit inside then check everything three times. .
Yeah what he said. Were those wrist pins from rods running in the motor? If so I think you will find much more grief that sleeving one cylinder will fix. Or were they just left in there somehow? I bored my 331 to use 354 pistons. Worked fine.
Total dissassembly to see what did or didn't happen. If a moron was sloppy enough to leave a tube cap in, he might have left 2 wrist pins. Really can't imagine 2 pistons coming apart w/o a "Oh shit" moment for the driver.
It's at the engine shop disassembled right now. I haven't spoken to my Dad in detail yet, so I'm not positive on the extent of the damage.
73RR says check everything twice if not three times _ believe it!! also clean everything out - every nook cranny and oil tube - don't forget to clean the rocker shafts out - if there is silicon in the engine it goes everywhere inc the oil supply to the rockers. Don't be scared to knock the end plugs out of the rocker shafts and scrub the hell out of it all.
When the motor gets pulled down, be sure and post how the wrist pins got in the pan. The only thing I can imagine is the piston pulling in half.
But what happened to the small end of the rod? I have had pistons fall in the pan but the wrist pin stayed with the rod. Really wore out the cylinder wall big time.
I hope you're talking wrist pin RETAINERS here and not wrist pins.....that would be some major SNAFU going on in there!!
Even if they were RETAINERS, how in hell would they wind up in the pan!...unless there is some MAJOR internal damage. Time to go down to the bare block...
OK, so it was two cylinders & it was the retainers, not the actual wrist pins. With the retainers loose, it allowed the wrist pins to bang back and forth inside the cylinders. Apparently going to .060 will clean it up, so Dad's pretty much decided to do new pistons/rings. Someone had mentioned to him that sleaving is not an option. I'm not really sure why not.
Since there is NO way for the retainers to escape the confines of the piston we are left to assume that the person assembling the engine simply used the oil pan as a waste basket...make damn sure that everything is cleaned and checked, not only for silicone contamination, but for whatever else the first guy did or didn't do... .
I would venture to say that sleeving 2 cylinders and using the old pistons, would be less exspensive than buying a new set of .060 overs and boring 8 holes...FWIW...
I had a 331 bored to a 354 way back. That was fairly common in the 1950's and 60's. The cast on upper bell housing was a bigger problem.
That's what I told him. I'm not sure why he's so set on boring all 8. There may be other details I'm not getting in the relayed masseage.
Hello: 1) Which of the Chrysler Hemis of 331, 354, 392 would have the thicker remaining wall thickness AFTER a .030 over bore? 2) Is there a 392 block of which is the most sought after/optimum? If so, why?
This sounds like a question that would be on "So you want to be a gearhead millionaire". HAHA! Would depend on a sonic check for actual measurements and it would also depend on if the 331 or 354 block is a truck block. My money is on 331 truck block having the thickest wall AFTER a .030" bore. But why would you need to know that???? Do you have some .030 over pistons for each size?? Are you just wondering, basically, which block would have the thickest walls at standard bore so you know which motor you could bore the hell out of??
Any hemi guy knows " as stated already", make sure those rocker shafts are clean inside, and make darn sure that the cam bearings are removed and replaced. 300 miles or not, you cant clean a block properly, unless you remove them. Rocker shafts and cam bearings, oil pump, and of course all oil galley plugs, NO MAYBE'S.
Not to hijack this thread, but have a '56 truck 331 that has the "W" cast on the side of the block. I have heard that these are really 354 blocks with a small bore and will go to 354 easily. Anyone know for sure?
Don't know. There are blocks with 354 casting numbers that are 331s. The assumption is they were underbored for some reason, maybe warranty replacements or maybe for heavy duty use. One of my blocks has a W, maybe I should look into a sonic check....
The Jalopy Journal
